Model 0662/20, chassis nos 06624001-06625665 fitted with the AEC 7.7 litre 6-cyl oil engine. This version was originally called the Mk II, but as Mk II had already been used for the prewar type 862/0862 it was quickly reclassified Mk I instead. This version differed from the prewar 0662/19 in having triple servo brakes.